The upper eyelid serves the important anatomic function of protecting the eye and rewetting the cornea to maintain vision. The complex dynamic action of the upper eyelid explains its relatively complex anatomy. The brow has an important supportive role. Studies have revealed facial characteristics perceived as youthful and aged, and the anatomic basis of these changes is defined at many levels. Characteristic aging changes in the upper eyelid and brow create an appearance of aging and opportunities for functional and aesthetic improvement.
Key points
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The complex anatomy of the eyelid and inter-relation of the eyelid–eyebrow continuum have important functional and cosmetic consequences in the periorbital region.
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A study of what is considered attractive, youthful, or aesthetically desirable is useful in patient evaluation and defining surgical goals.
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Characteristic aging changes in the central face have a definable anatomic basis and cosmetic consequences amenable to surgical correction.
Brow and upper eyelid anatomy
The eyebrow and upper eyelid comprise the periorbital area. In considering rejuvenation of the aging face, this zone is evaluated and treated as a single area, because there is an intricate interaction between the eyebrows and the upper eyelid in the aging process. This intricate and interdependent relationship extends into the forehead and frontalis muscle in a relationship defined by Hering law. The periorbital region is bounded superiorly by the forehead and laterally by the temporal region. They meet centrally at the glabellar region. Lower eyelid anatomy, aging, and surgical treatment are covered elsewhere in this issue.
Brow and upper eyelid anatomy
The eyebrow and upper eyelid comprise the periorbital area. In considering rejuvenation of the aging face, this zone is evaluated and treated as a single area, because there is an intricate interaction between the eyebrows and the upper eyelid in the aging process. This intricate and interdependent relationship extends into the forehead and frontalis muscle in a relationship defined by Hering law. The periorbital region is bounded superiorly by the forehead and laterally by the temporal region. They meet centrally at the glabellar region. Lower eyelid anatomy, aging, and surgical treatment are covered elsewhere in this issue.
Eyebrow soft tissue
The eyebrow is comprised of the skin and soft tissues that cover the superior orbital rim. Visually it is demarcated superiorly by the first forehead crease that curves above the hair bearing brow skin. Inferiorly the subciliary brow ends at the arcus marginalis on the superior orbital rim, transitioning to the upper eyelid. The upper eyelid extends inferiorly to the upper lid margin inferiorly apposing the globe ( Fig. 1 ).
The eyebrow skin contains specialized hair follicles that define the brow. These hair follicles are different from other follicles in their orientation and growth cycle. Unlike hair follicles of the scalp, the brow cilia have a limited growth pattern and can be permanently injured with plucking or shaving. Once lost, the brow cilia are difficult to recreate with grafting. Deep to the hair-bearing skin of the brow is the corrugator supercilii muscle ( Fig. 2 ), which originates from the superior orbital rim at the medial end of the brow and runs along the superior orbital ridge for a variable distance to terminate at the lateral third of the brow. The corrugator muscle inserts into the brow skin and is responsible for the vertical lines in the glabellar region perpendicular to its orientation. The procerus muscle lies in the midline of the glabellar region extending inferiorly from the nasion and oriented in a vertical fashion. Contraction of this muscle creates the horizontal lines that appear in the central glabellar region and upper nose. Both the paired corrugator supercilii muscles and the central procerus muscle are strong depressors of the eyebrow.
There is a dense fibrous attachment of the brow to the superior orbital rim that extends inferiorly to the arcus marginalis of the superior orbit. The superior and upper lateral orbital rims complete the osseous boundary of this region.
Eyebrow innervation and vasculature
Piercing the superior orbital rim through a complete foramen, or traversing through a notch, are the supratrochlear and supraorbital nerves; both are branches of the first division of the trigeminal nerve. The supratrochlear nerve is located approximately 17.5 mm from the midline along the orbital rim. Often a notch can be palpated there. Traversing with the supraorbital nerve is a paired artery and vein of the same name. The supraorbital nerve is located approximately 27.5 mm from the midline along the superior orbital rim. It may traverse through a true foramen or a notch. It also has a paired artery and vein of the same name. These 2 sensory nerves exit the superior orbital rim and ascend up the forehead, providing sensory innervation to the forehead and scalp to the vertex. The supratrochlear nerve branches medially to provide sensory innervation to the glabellar region and upper lateral nose as well. There is also a small infratrochlear nerve that exits inferior to the supratrochlear nerve and supplies sensation to the side of the nose and medial canthal area.
Motor innervation for the corrugator and procerus muscles is via branches of the upper division of the facial nerve. Lymphatics in this region generally run with the neurovascular bundles and also laterally from the lateral orbital rim.
Hering law
Ewald Hering described a symmetric and synergistic relationship of the eye muscles that allowed an individual to track a moving object and to keep that object in focus and fuse images from the 2 eyes. Information from the afferent system provides a symmetric feedback loop to the extraocular musculature that allows this to occur. This same principle applies to the levator superioris and frontalis muscles. If significant dermatochalasis or lid ptosis exists, the levator palpebrae superioris and/or frontalis muscle tone is increased to overcome this inferior displacement of the eyelid. This compensatory hyperactivity of the frontalis muscle is evidenced by increased horizontal forehead rhytids. It is essential to examine the patient with the frontalis muscle relaxed to accurately determine brow position and the presence of lid ptosis. Likewise, when significant brow ptosis is present, it is important to examine the eyelids with the brow in a more youthful elevated position to determine the true extent of the dermatochalasis. Patients are often surprised to see how little dermatochalasis they have when the brow is elevated. Blepharoplasty surgery often unmasks latent lid ptosis or brow ptosis secondary to Hering law. This is because correction of the dermatochalasis diminishes the afferent input to the frontalis and levator muscles, which then relax, revealing the true brow or lid ptosis.
Neuromodulators
It is important to evaluate patients without neuromodulators such as botulinum toxin in effect. Depending on where the botulinum toxin is placed, the brow can be lowered (frontalis muscle injection) or raised (orbital portion of orbicularis oculi). Patients should always be asked about the use of neuromodulators.
Eyelid soft tissue
The function of the upper eyelids is to protect and lubricate the cornea by acting as a barrier to foreign bodies and by restoring the tear film through periodic blinking. Small glands along the lid margin secrete mucous and oil that adds to aqueous lacrimal gland secretion, creating a 3-layer tear film that lubricates the cornea. This tear film breaks down as it is exposed to the air, and the act of blinking restores this delicate balance.
The upper eyelids are composed of several layers ( Fig. 3 ). These are typically broken down into the anterior and posterior lamellae. The anterior lamella is comprised of skin and orbicularis muscle. The skin of the eyelids is the thinnest skin of the human body. This provides the necessary flexibility needed for blinking. Because it is so thin, it contains few sebaceous glands or adnexal structures. There is also no fat or adipose layer between the skin and the underlying muscles below the preseptal orbicularis. The posterior lamella is composed of the levator muscle and/or levator aponeurosis, Müller muscle, and conjunctiva. Inferiorly, the posterior lamella contains the tarsus instead of the muscle/aponeurosis layer. The tarsus is a specialized dense connective tissue structure that acts as the skeletal support or framework for the eyelid. Within the tarsus are the meibomian glands that secrete mebum, a thick lubricant that contributes the oil layer to the tear film. The lid margin has a tightly adherent mucosal layer that is penetrated by the meibomian ducts. The upper tarsus measures approximately 10 to 12 mm in height at the midpupillary line and tapers medially and laterally. The tarsus is held tightly in position laterally by the upper crus of the lateral canthal tendon, which inserts laterally onto Whitnall tubercle, a bony prominence just inside the orbital rim ( Fig. 4 -G ). The medial canthal tendon divides into anterior and posterior divisions that encircle the lacrimal sac. They insert on the anterior and posterior lacrimal crest, respectively. The orbital fat is separated from the posterior lamella by the orbital septum, which is a thin adventitial layer that fuses with the superior edge of the tarsus inferiorly and with the arcus marginalis superiorly.
Musculature
The orbicularis muscle is a radially oriented muscle that is innervated by the facial nerve and is responsible for the radially oriented crow’s feet lines that appear at the lateral canthus over time. The orbicularis muscle has 3 components ( Fig. 5 ):
The orbital portion is the outermost portion of the muscle, and it overlies the superior bony rim and contributes fibers to the cheek, forehead, and temporal region. This portion of the orbicularis is a significant depressor of the eyebrow along with the corrugators and procerus muscles.
The preseptal component lies between the orbital and pretarsal components.
The pretarsal component overlies the tarsus. The preseptal and pretarsal components perform the involuntary blinking function of the eye.
The levator palpebrae superioris arises from the lesser wing of the sphenoid at the orbital apex and is continuous with the levator aponeurosis, inserting onto the anterior surface of the tarsus (see Fig. 3 ). It is innervated by the superior division of cranial nerve III and serves as the primary elevator of the eyelid. At the posterior surface of the levator aponeurosis and attached to the palpebral conjunctiva, is Müller muscle, innervated by the sympathetic nervous system, which travels via the carotid artery to the ophthalmic vessels and into the muscle. Müller muscle is responsible for 2 to 3 mm of elevation of the upper eyelid as a resting tone and not a voluntary contraction. Disruption of the sympathetic chain along the carotid artery is responsible for Horner syndrome, characterized by lid ptosis, miosis (constricted pupil), and anhydrosis (lack of sweating) of the ipsilateral face.
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